Signaling system



Sept. 3, 1940. c. J. FITCH SIGNALING SYSTEM 2 Sheets-Sheet Filed Nov. 10, 1938 O B ATTORNEY Patented Sept. 3, 1940 PATENT OFFICE SIGNALING SYSTEM Clyde J. Fitch, Endicott, N. Y., assignor to international Business Machines Corporation, iii cw York, N. Y., a corporation of New York Application November 10, 1938, Serial No. 239,837

3 Claims. (Cl. 178-51) This invention relates to signaling systems and more particularly to a system for operating remotely situated signaling channels in timed relationship. v

The instant application constitutes an improvement over the signaling system described in the co-pending application, Serial No. 756,443, filed December 7, 1934, wherein said co-pending application a plurality of normally non-conductive signaling channels are provided at a transmitting and receiving station, each channel including an electric discharge device; and wherein individual sources of fluctuating voltages are transformed into polyphase voltages which at each station are impressed upon the signaling channels for conditioning the channels period ically and cyclically at mutually exclusive intervals for control purposes. Signal initiating and indicating means are described in detail in the said co-pending application, and are shown to control selectively the signaling channels at the transmitting station to render them conductive upon operation of the signal initiating means for initiating code combinations of control signals which are efiective to render the receiving signaling channels conductive in accordance with the receipt of the signals for controlling selectively the signal indicating means. It was mentioned that individual sources of voltages are provided for conditioning the signaling channels, and assumed, that the said remotely situated sources of voltages are obtained from synchronous voltage distrlbution systems.

It is known that for certain applications that such synchronous sources of voltages are not available and that therefore additional provisions must be made for controlling the synchro nous conditioning ofthe said signaling channels. It is now proposed that the transmitting station control the synchronous conditioning of the signaling channels at both stations.

To this end certain of the available signaling channels are employed for synchronizing purposes, that is, at the transmitting station a predetermined number of signaling channels are normally maintained non-conductive and disconnected from the transmission medium for signal control :purposes as described in the said co-pending"-application, and that, for example, a single signaling channel is connected at all times to the transmission medium, so that upon the periodic and cyclic conditioning of the last mentioned channel periodic synchronizing signals are impressed continuously upon the transmission medium. In this manner, the normally non-conductive channels are selectively rendered conductive in accordance with the operation of the signal initiating means for initiating combinations of timed control signals and the selected channel for synchronizing control purposes is effective con- 5 tinuously for initiating periodic synchronimig signals.

At the. receiving 'station a corresponding signaling channel is selected to be responsive to the synchronizing impulses which upon receipt 19 thereof is effective for controlling the generation of a fluctuating voltage supply which in turn is transformed into a polyphase' voltage supply and impressed upon the signaling channels thereat for conditioning said channels in timed relationship with the signaling channels at the transmitting station.

Therefore, an object of the present invention resides in the provision of a synchronizing control channel ,including an electric discharge device 20 which is conditioned and rendered conductive at periodic intervals by a fluctuating power supply impressed thereon'for initiating continuously a series of periodic synchronizing impulses which are transmitted for rendering a synchronizing control channel remotely situated therefrom operative upon the receipt of the synchronizing" signals for controlling the generation of a fluctu ating power supply thereat in timed relationship with the first mentioned power supply.

Another object of the'present invention resides in the provision of a'plurality of non-conductive signaling channels at both the transmitting and receiving stations and conditioning the signaling channels periodically and cyclically at mutually exclusive intervals for controlling purposes and in addition thereto providing at the transmitting -station means to transmit continuously periodic synchronizing impulses. the receipt of which at the receiving station is eiiective to ren- 4 der the synchronizing channel thereat conductive for controlling the subsequent conditioning of the signaling channels thereat.

Further objects of the instant invention reside in any novel feature of construction or operation or novel combination of parts present in the embodiment of the invention described and shown in the accompanying drawings whether within or without the scope of the appended claims and irrespective of other specific statements as to the scope of the invention contained herein.

In the drawings:

Fig. 1 is a circuit diagram showing diagrammatically the circuit arrangement of the signaling and synchronizing channels at the transmitting and receiving station.

Fig. 2 shows diagrammatically one form of a phase-splitting transformer employed at the transmitting station. n

Fig. 3 shows diagrammatically one form of phase-splitting means employed at the receiving station.

Fig. 4 shows one form of impulse generator employed at the transmitting station.

Fig. 5 shows one form of impulse generator employed at the receiving station.

Figs. 6-8 show the voltage wave-shaped forms impressed on the various sections of the transmitting circuits.

Figs. 9-12 show the voltage wave-shaped forms impressed on various sections of the receiving circuits.

Fig. 13 shows graphically the developed phasedisplaced impulses representing the differential times at which the electric discharge devices at both the transmitting and receiving stations are rendered conductive.

GENERAL DEscam'roN Referring now to Fig. 1, the signaling system is shown to comprise a plurality of signaling channels including electric discharge devices T-| to T-8 and R-I to R-8 at the transmitting and receiving stations respectively. The series of electric discharge devices at the transmitting station are shown associated with a phasesplitting transforming means generally indicated by the reference character III which is shown in detail in Fig. 2. The series of electric discharge devices at the receiving station are similarly shown to be associated with a phase-splitting means I I which is shown in detail in Fig. 3. Individual sources of fluctuating power are impressed upon the phase-splitting transforming means which are efl'ective to generate phase displaced voltages which are impressed upon the associated electric discharge devices. The said discharge devices at both the transmitting and receiving stations are conditioned for controlling purposes by the fluctuating power supplies periodically and cyclically at mutually exclusive intervals. The devices at the transmitting station are rendered conductive selectively upon operation of the signal initiating means generally indicated by the reference character It. It is suflicient to mention that the signal initiating means I! may be operated singly or simultaneously in diflerent code combinations for initiating code combinations of signaling impulses. Devices for controlling the signal initiating means in selective combinations are well known in the art, and since these devices per se form no part of the invention, further description thereof is deemed unnecessary. However, reference may be made to the above mentioned application, or to copending application, Serial No. 113,798, filed December 2, 1936, wherein methods of conditioning and controlling the signal initiating means are shown and described in detail.

It is to be noted that normally the signal initiating means l2 maintain the electric discharge devices T-l to T8 disconnected from the transmitting circuit arrangement, whereas the synchronizing channel, including the electric discharge device T-fl, is at all times connected thereto for impressing continuously thereon the periodic synchronizing impulses.

At the receiving station the devices R--l to R- are rendered conductive in accordance with the combinations of the control signals received for controlling the energization of the signal indicating control means indicated generally by the reference character l3. Such signal indicating means controlled by combinations of signals are well known in the art and need not be disclosed in detail; however reference is made to the above mentioned co-pending application or the co-pending application, Serial No. 178,016, filed December 4, 1937, wherein methods of conditioning and controlling signal indicating means are shown and described in detail.

The synchronizing channel including the electric discharge device R-8 is conditioned and controlled continuously by the received periodic synchronizing signals for controlling periodically the energization of a circuit tuned to the frequency of the synchronizing signals thereby generating a periodically fluctuating power supply which in turn is impressed upon the phase transforming means thereat. The said phase transforming means is eflective to condition the associated signaling channels controlling the conductivity thereof periodically and cyclically, and in synchronism with the conditioning of the signaling channels at the transmitting station. Segregation of the received character signals is effected by the signaling channels which are conditioned in synchronism therewith, thereby rendering the desired channels conductive for controlling the associated signal indicating control means.

Transmitting station Phase transforming means.Referring now to Fig. 2, it will be shown how the fluctuating voltage supply is transformed into a polyphase source of supply which is employed for conditioning the signaling channels at the transmitting station. In the said figure the phase transforming means I0 is shown to comprise two transforming means including the primary windings l5 and I6 and the corresponding secondary windings l5a to [5-91 and IG-a to l6g. A condenser I1 is provided in the primary circuit of one and an inductance l8 in the primary circuit of the other, so that the voltages in said circuits are ninety degrees out of phase. It is to be noted that the turns ratio of the individual secondary windings vary for each phase connection and the turns ratio of the separate connected windings of both transformers are such that the voltage output for the open circuits are equal. The phase direction is shown vectorially by the arrows for each separate phase developed. This arrangement and connection of the primaries and secondaries of the transforming means results in eight separate secondary circuits as shown spaced twentytwo and a half electric degrees apart, each phase of which is adapted to deliver equal voltages across the free ends of the secondary circuits. In the present invention the described phase splitter is employed solely at the transmitting station as indicated in Fig. 1. Any suitable fluctuating power supply may be connected to the terminals I! of the phase transforming means, for example, the said terminals may be connected to the present day distribution systems furnishing the standard sixty cycle power supply.

Channel conductizfity controlling means.-.-Re-

ferring now to Fig. 4, an individual electric dis:-

wave rectifier and triode in one envelope and which is well known in the art, commonly referred to as a duplex diode triode type." The diode plates 20 are joined to the terminals of anyone of the said secondary windings of the phase transforming means, in the example chosen, indicated as -I.a, and the shunt connected resistor 2|, the center tap of which is connected to the grid control element 22 of the device T-l and by means of the resistor23, is also joined to the cathode 24 thereof. It is evident from this description that normally the .grid element of the device is at zero bias, since no current is impressed upon resistor 23; therefore, upon closure of the signal initiating means shown as contacts l2 a momentary current flow is established in the triode plate circuit as follows: from the positive terminal of the battery A to the primary winding of transformer 25, anode and cathode of the device T--| to the negative terminal of the said battery. This described condition exists in the circuit for only a comparatively short time, because the bias on grid 22 remains no but varies in a timed relationship with the frequency of the fluctuating supply source. The said supply source by means of the, winding l5a is impressed upon the full wave rectifier section of the device and the rectified voltage impressed upon resistor 23 immediately drives the grid bias negative with respect to the cathode. The value of the resistor 23 is adjusted so that before the grid-bias becomes efiective' to reduce the plate current to substantially zero value, a pulse is impressed upon the output circuit just .traced so that a short signal impulse is impressed on the output circuit connected to the secondary wind ing of transformer 25. It is understood now that, if the signal initiating means I2 is maintained in an operated position, the device T-l is rendered conductive so that a series of short equally spaced impulses will be continuously impressed upon the said output circuit and that the frequency of the initiated signal is twice the frequency of the fluctuating supply source. Referring to Figs. 6 to 8, the voltage wave forms impressed upon different sections of the circuit are shown, Fig. 6 represents the sinusoidal wave shape of the voltage impressed upon the diode .plates 20 of the device; Fig. 7 represents the rectified wave forms impressed upon the resistor 23, andthe wave forms shown in Fig. 8, represent the impulses generated and impressed upon the output circuit of the device each time the said device is rendered conductive, which as described, is at those times that the said voltage supply passes through zero value.

Transmitting circuit arrangement.Referring now to Fig. 1, the operation of the signal generating and transmitting circuits will now be understood. The individual signaling channels including the electric discharge devices Il to T-B are connected to the individual output circuits of the phase transforming means l0, several circuits of which are shown in detail.,' The signal initiating means l2 included in the individual signaling channels are connected in common to signal transmitting means 26 which may be one of any of the known types of signal transmitters. As mentioned hereinabove, the signal initiating means l2 may be operated singly or in different code combinations by the mechanisms referred to in the said co-pending applications for controlling the conductivity of the individual signaling channels associated therewith. Upon operation of any of the signal initiating means l2, equally spaced timed signals will be initiated;

the timing of the out of phase control signals with respect to each other is controlled by the phase displaced voltages impressed upon the input circuits of the electric discharge devices. The signaling channels just referred to relate to those associated with phases l to 6 of the phase transforming means Ill. Phase I is not shown to be included in the transmitting and receive ing circuits; this phase may be used for other controlling piu'poses not relevant to the present invention. Phase 8 of the phase transforming means -I 0 is shown connected to a signaling channel which will be referred to hereinafter as the synchronizing control channel and is shown to include the electric discharge device T8 similar to those just described but is shown to be connected directly to the common conductor which is connected to the primary winding of the transformer 25. Therefore, it is seen that each time the fluctuating voltage supply of phase 8 passes through zero the signaling channel and signal initiating means l2 are operated singly.

naiing channels including the devices Tl to T6 conductive for initiating variably timed control signals.

As mentioned hereinabove, the initiated signals are impressed upon any suitable transmitting means indicated generally at 26 by means of the transformer 25, which signals may then be transmitted over any suitable transmission medium to the remotely situated receiving station where the signals are impressed upon suitable receiving means indicated generally by the reference characters 21 and 28.

Receiving station Phase transforming "Leann-Referring now to Fig. 3, the phase transforming means ll associated with the signaling channels at the receiving station including the electric discharge devices R--| to R-8 will now be described.

It is to be noted that the phase splitter shown in Fig. 3 is differently arranged as compared with the phase splitter Ill associated with the signaling channels at the transmitting station. The phase transforming means I0, as stated, is capable of generating eight different phases, whereas the transforming means ll shown in Fig. 3 is capable of generating only four different phases but providing two output circuits for each of the fourindividual phases. The purpose of the arrangement of transforming the fluctuating power supply impressed on the terminals 30 into four phases equally spaced and the double or twin secondary windings so that eight secondary circuits are available will be understood as the description progresses. In the circuit including the primary winding 3|, a condenser 32 is included, and in or in combination to render the associated sig-' voltages in the said primary windings are ninety degrees out of phase, the voltage across each primary winding being the same. It is to be noted that the turns ratio of some of the individual secondary windings vary so that the voltages across the said windings vary accordingly; for example, the secondary windings associated with the primary winding 3| comprise two windings 3la and 3l-d of voltages E and four windings 3l--b, 3lc, 3le and 3|.f of voltages equal to /2 E. The secondary windings 33a to 33f associated with the primary winding 33 are similarly rated, and therefore, the output voltages of the connected secondary windings are all of equal values. It is evident from the description thus far that four different phases equally spaced electrically, namely, forty-five .degrees apart, are developed. The phase directions vectorially are shown by the arrows for each of the phases in the said figure. As mentioned hereinbefore, the output circuits of the secondary windings are arranged in pairs, that is, two circuits are provided upon which the same phases are impressed, such as the circuits indicated by the reference characters l and 5 in Fig; 3, or circuits 3- and I.

Channel conductivity controlling meana-Referringnow to Fig. 5, one type of electric discharge circuit which may be associated with the second= ary output of the phase transforming means II and included in the individual signaling channels at the receiving station will now be described. The electric discharge device RI is shown to comprise a full wave rectifier and triode device in one envelope similar to the device T-l in Fig. 4. The associated circuits are similar to those described in connection with electric discharge device Tl shown in Fig. 4 with the exception of the additional provision of the condenser 35 connected between one of the diode plates 20a of the device R-l and the associated cathode.

It is evident now from the description set forth hereinabcve that the grid element 22a of the device R-l is at zero bias when the fluctuating supply impressed on the secondary winding of the transformer, for example, 3l-a, passes through zero due to-the fact that no current is passing through the resistor 23-a. It is at such periods that the device Rr-l is conditioned to be conductive thereby permitting current to flow in the associated output circuit. It was mentioned, however, that condenser-35 is inserted between the cathodeand one of the diode plates 2ll-a as shown in Fig. 5: The curve in Fig. 6 shows the voltage wave form impressed across the diode plates of the device R-|. When the polarity is such that current passes from one diode plate 20a to cathode, this current passes through the resistor 23a and also charges the condenser 35 to the polarity as shown. At the end of this particular half cycle as the current passes through zero, the charge in the condenser maintains the grid of the device negative with respect to the cathode and is of such value as to be suiflcient to permit no plate current to flow. The charge in the condenser leaks off through the resistor 23-11, ,the value of the capacitor and resistor being such that the time constant of the circuit is adjusted so as to maintain the device non-conductive during the timed interval that the said half cycle of the power supply passes through zero, and during part of the following half cycle until the current passing from the other diode Ill-a to the capacitor and through resistor 23a has reachedsuflicient amplitude to maintain the device biased so as to be maintained non-conductive. At the end of the second half cycle the charge in condenser 35 has completely leaked ofi and, as the said half cycle passes through zero, the grid bias is zero, thereby permitting the device to be rendered conductive momentarily. Thus, it is seen that during the transition period during the first and second half cycle the device is continually rendered non-conductive and during the transition period between the second and third half cycle, the condenser having received no charge during the second half cycle, or if any charge, it is in the opposite phase, thereby having no eifect upon the bias and thus permitting the device to be conductive as the fluctuating voltage supply passes through zero.

The curve shown in Fig. 9 shows the wave shapes of the rectified voltage across the resistor 23-41. The effect of the condenser 35 is evident, suppressing the alternate peaks of the rectified wave as shown and as just explained the suppressed waves are effective to maintain the bias of the device such as to render the device nonconductive, whereas the unsuppressed waves are effective to render the device conductive. Thus, it is seen that the device is rendered conductive one time for each complete cycle of the fluctuating power supply impressed thereupon, whereas without the condenser the said device would be rendered conductive two times over a complete cycle of fluctuating power supply.

In Fig. 10 the impulses indicated therein are representative of the periods at which the device is rendered conductive and the short current impulses flowing in the output circuit of the device at such times which as seen from the figure occurs at equally spaced timed intervals. that the condenser 35 is connected in the diode plate circuit opposite to that shown in Fig. 5, for example, between the cathode and diode plate 2ll--a farthest to the left as viewed in the said figure. With the condenser inserted in the assumed circuit, it is obvious that the opposite peaks of the rectified wave forms will be suppressed and render the tube non-conductive. In Figs. 9 and i 10 the wave forms are shown when the condenser 35 is included in the circuit as shown in Fig. 5. Figs. 11 and 12 show the wave forms in the circuit when the said condenser is inserted in the other diode plate circuit. The impulses in Figs. 10 and 12 indicate comparatively the timed intervals during which the device Rl is rendered conductive.

Receiving circuit arrangement-Referring now to Fig. 1, the operation of the receiving circuit will be described briefly. The individual receiving signaling channels including the electric discharge devices R-l to R-B are shown connected to the individual output'circuits of the phase transforming means, ll, several circuits of which are shown in detail. It is to be noted that the output circuits of the phase transforming means, designated phases I to 4, are equivalent in phase direction to those phases designated 5 to 8. That is, the phase direction of phases l and 5, 2 and 8, 3 and 1, l and 8, are the same direction and are of the same voltage values. For this reason, it is to be noted that the condensers 35 associated with the circuits of the devices R-l to R4 are inserted in one leg of the diode plate circuit, whereas for the devices R 5 to R-8 the condensers are inserted in the other leg of the diode plate circuit. The reason for this will be understood as NOW assume the description progresses. The plates of the triode element of the devices R-l to R---. are connected in common by the circuit 4lto the cathode element of the control tube 42. The control grid elementgof this last mentioned tube is shown associated with the signal receiving means indicated generally by the reference characters 21 and 28. The tube 42 is normally biased so as to be non-conductive during the intervals that no signals are impressed upon the control grid element thereof. The grid bias voltage for this tube is supplied by the rectified voltage generated by the rectifier unit of the tube 42 and impressed upon the resistor 43. The voltage impressed upon this said resistor-maintains the grid circuitbiasedsothatnocurrentcanbepassedin' the triode element of the tube unless the control signals received by the signal receiving means or impressed upon the grid element thereof.

The individual electric discharge devices R-l to 3-! are shown to be associated with individual condenser units 6-! to (3-4 which in turn are adapted to control the grid circuits of the associated tubes A-I to A-6. The selective controlling of these circuits will be explained later herein; however, it should be mentioned that the tubes 'A-l to A-6 are-normally biased so that they remain non-conductive and in this manner maintain the signal indicating control means ll deenergized until such times when the particular control signals are received and impressed upon the receiving circuit arrangement. As mentioned hereinbefore, the signaling indicating control means may be controlled singly orin various code I combinations.

Now assume that at the transmitting station the phase transforming means III is connected with a suitable fluctuating voltage supply. For example, a standard commercial sixty cycle voltage supply and assume that the signal initiating means I! remain unoperated. It isseen that a plurality of synchronizing control impulses are generated by the synchronizing channel including for each synchronizing impulse received the tube 42 is rendered conductive momentarily permitting current to flow through the following circuit: from the positive terminal of the battery B, condoctor 44, anode and cathode elements of tube 42,

conductor 4|, anode and cathode elements of the device 3-8, resistor 45, common conductorj46 to the negative terminal of the said battery. The

signal impulses impressed across the resistor 45 are in turn then impressed across the resistor 45-a are in turn then applied to the grid element of the tube A8. This last mentioned tube is normally biased so that the tube remains nonconductive until the impulses are impressed upon the associated control grid element. Upon rendering the tube A-8 conductive momentarily whenever the impulses are impressed upon the resistor 45 the current impulses thereof are im-' pressed in turn upon the tuned circuit generally indicated at 41. Assume that the said tuned circuit 41 is tuned to 120 cycles, therefore, it is seen when the synchronizingimpulses are impressed upon the resistor 45 at the rate of 120 impulses per second a. 120 cycle sine wave is generated by this tuned circuit which in turn by means of transformer 48 is impressed. upon the amplifier tubes 49 connected in push pull arrangement to energize and render these last men-- tioned tubes conductive. The output of the tubes 48 is impressed by-the transformer 50 upon the input circuit of the phase transforming means I i. From the description thus far, it is seen that a 1.20 cycle voltage supply is generated by the tuned circuit arrangement just described, the energization of which is controlled by the'tube A-8 and the synchronizing channel including the device R 8. The 120 cycle power supply is then transformed into two phases ninety degrees apart by tioned that eight secondary or output circuits are provided by the phase transforming means. In this manner two output circuits each are provided for the phases one to four, each of the phases being spaced forty-five electrical degrees apart. It was also mentioned that the output circuits forthe first four. phases where connected to the receiving signaling channels in-, cluding the devices R l to 3-4, each of which are adapted to have the condenser 35 inserted in one and the same legs of the diode plate circuits thereof. Therefore, it is seen that the first four signaling channels including the devices R-l to R-4 are conditioned by the phase transforming means and the 120 cycle power supply impressed thereon to control the conductivity of these said devices so that the devices can be rendered conductive one time each cycle,

ply and it is remembered that the signaling channels are adapted to,be conditioned two timw for each cycle which for the example chosen would be at the rate of 120 times per second. Therefore, it is seen that the first four channels of the transmitting circuit, and the first four channels of the receiving circuit,-are. conditioned to control, the conductivity of the associated devices, namely, T-l to T4 and R'-l to R-4 respectively at the same intervals periodical and cyclically.

The output circuits of the phase transforming means H for the phases 5 to 8 are connected to the signaling receivingchannels including the devices R-5 to R-8 which, as mentioned hereinbefore, are adapted to have the individual.

press the alternate waves which were efiective to condition the first group of devices R-l to R-l to control their conductivity. The result of the arrangement just described in connection with the receiving circuit is that each of the signal receiving channels are conditioned 120 times per second so as to permit the devices R--l to R-8 to become conductive, and that each of the said channels are conditioned successively similarly as the signaling channels of the transmitting circuit arrangement are conditioned and, in accordance with the example chosen, the individual and successive conditioning of the signal transmitting and signal receiving channels occurs every one-nine hundred and sixtieths of a second which is equivalent to twenty-two and a half electrical degrees of a sixty cycle power supply and forty-five electrical degrees of a one hundred twenty cycle power supply. Referring to Fig. 13 the timing arrangement just explained is shown graphically therein, the impulses for each phase representing the times at which the individual channels associated with each of the phases are conditioned to control the'conductivity of each of the channels. It is seen that each channel is conditioned periodically'and cyclically and that the conditioning of each channel occurs at mutually exclusive timed intervals.

It should be mentioned that upon initial conditioning of the transmitting and receiving circuits, that is, upon conditioning the signaling system with the synchronizing signals, before initiation of the character signals, that as soon as the first synchronizing signal is impressed upon the receiving circuit arrangement not only is the synchronizing channel associated with phase 8 of the phase transforming means II and including the device R-8 rendered con- 40 ductive momentarily, but similarly are the other signal receiving channels associated with phases l to 8 and including the devices R--l and R4. However, the individual signal receiving channels can be so arranged that the momentarily period of conductivity of these channels effects no faulty operation of the associated signal indicating control means. This can be effected by selecting the capacity elements C-| to 0-4 to be of such value so that a predetermined number of received impulses are necessary before the individual capacity elements are effective to overcome the .individual grid bias impressed upon the grid control elements of the tubes Al to A'6. It is seen that immediately upon operation of the first synchronizing impulses that the cycle power supply is instantly generated and impressed upon the phase transforming means so that control of the signal receiving channels is immediately established; and since the synchronizing signals are the only signals being received at this time and since the synchronizing channel including the device R8 is the only channel in phase with the incoming synchronizing signal, consequently the receipt of the synchronizing signal is no longer efiective to render the remaining signaling channels conductive.

In order to describe briefly how the individual signaling channels may be rendered conductive for signaling control purposes assume that the signal initiating means l2 at transmitting station associated with the signal channel including the device T-l is operated thereby initiating a series of particularly timed impu ses which are impressed upon the signal transmittlnfl means 25 and 26. It is understood that the character signals initiated and generated thereby are impressed upon the signal transmittin means in addition to the periodically timed synchronizing impulses which are continuously generated by the synchronizing channel including the device T--8 and impressed upon the s18- nal transmitting means. The continuously initiated synchronizing impulses are effective at all times to control the synchronizingchannel at the receiver thereby controlling the generation of the 120 cycle power supply which in turn is im-- pressed upon the phase transforming means II which in turn controls the segregation of the timed character signals which are initiated and generated aperiodically upon operation of the different signal initiating means l2. Continuing now with the example, the character signals generated by the signaling channel including the device T--l are impressed upon the signal receiving meansfl and 28 to render the tube 42 conductive, thus permitting current to flow in the following circuit: from the positive terminal of battery B to conductor 44, anode and cathode elements of tube 42, conductor ll, anode and cathode elements of device R-l, conductor 52, condenser C-l and resistor Ll to the negative terminal of the said battery. Upon energization of the described circuit by the series of character impulses impressed thereon the condenser (1-4 is charged by a predetermined number of the said series of impulses and the resulting voltage drop across the resistor L-l is effective to reduce the bias on the associated grid element of the tube Al thereby permitting current to flow in the output circuit of the tube A--l includin the signal indicating control means I3. It is seen that the said signal indicating control means is energized as long as the signal initiating means I! associated with the device T--l is operated. It is understood from the description just set forth that the remaining signaling channels including the devices R--2 to R -6 are not rendered conductive at the times that the character signals are received which are generated by the signal initiating means associated with the first signaling channel including the device T--l.

It is evident now that the conditioning of the remaining signaling channels including the said devices R--2 to R-G is such that these remaining channels are not adapted to be rendered conductive at the same timed intervals the said character signals, initiated by device Tl, are received. It is seen that the signaling channel, at the receiving station, associated with the output circuit of phase I of the phase transforming means is conditioned so that the conductivity of this channel is controlled to hem synchronism with the conditioning of the signaling channel associated with the output circuit of phase i of the phase transforming means ill at the transmitting station. Similarly the signaling channels at the receiver associated with the remaining phases 2 to 8 of phase transforming means II are conditioned in synchronism with the signaling channels at the transmitting station associated with the phases 2 to 8 of the transforming means l8.- It is evident then that the individual signaling channels at the receiving station associated with the different phase output circuits are adapted to be responsive solely to the signals initiated by the sponding phases of the phase transforming means at the transmitting station.

It is seen, therefore, that after initial transmission of the periodic synchronizing signals said synchronizing signals are effective at the receiver to control a synchronizing channel and to control the generation of the power supply which, in turn, is impressed upon the phase transforming means for controlling the operation of the receiving signaling channels so as to beoperated in synchronism with the control signals, whereby, the signaling channel condi tioning means and the transmitting signaling channels can be operated singly or in various code combinations to initiate timed character signals which, in turn, are segregated by the conditioned signaling channels at the receiver and upon segregation thereof the said receiving signaling channels are rendered conductive to control the associated signal indicating control means accordingly.

While there has been shown and described and pointed out the fundamental novel features of the invention as applied to a single modification it will be understood that various omissions and substitutions and changes in the form and. details of the devices illustrated and in its operation may be made by those skilled in the art without departing from the spirit of the invention. It is the intention, therefore, to be limited only as indicated by the scope of the following claims.

What is claimed is:

1. A signaling system comprising a plurality of stations, a series of electron discharge devices at each station, means at each station for conditioning each of the devices of the series thereat sequentially and independently with respect to each other including means for controlling the conductivity of the devices of the series periodically and cyclically so that each device can be rendered conductive only at exclusive and predetermined intervals and rendered non-conductive at all other times, means at one of the stations for rendering a predetermined number of the conditioned devices conductive aperiodically at the said intervals ior initiating control signals, means at a second one of said stations for rendering the conditioned devices thereat conductive for segregating the said control signals for control purposes, means at the first mentioned station for rendering at least one of the said remaining devices conductive for initiating continuously a series of synchronizing signals at those intervals when the last mentioned device is conditioned so that it can be rendered conductive, and means responsive to said synchronizing signals at the second mentioned station including means for controlling the said conditioning means thereat.

2. A signaling system comprising a plurality of stations, aseries of electron discharge devices at each station,.means at each station including a fluctuating power supply for conditioning each of the devices thereat sequentially and independently with respect to each other including additional means for controlling the conductivity of the devices of the series periodically and cyclically so that each device can be rendered conductive only at exclusive and predetermined intervals and rendered non-conductive at all other times,

means at one of they stations for rendering a predetermined number of the conditioned devices conductive aperiodically at the said intervals for initiating control signals means at a second one of said stations for rendering the conditioned devices thereat conductive for segregating the said control signals for control purposes, means at the first mentioned station for rendering at least one of the said remaining devices conductive for initiating continuously a series of synchronizing signals at those intervals when the last mentioned device is conditioned so that it can be rendered conductive, and means responsive to said synchronizing signals at the second mentioned station including means for controlling the generation of the fluctuating power supply thereat. i

3. A signaling system comprising a plurality of stations, a series of electron discharge devices at each station, a multi-phase power supply at each station, means at each stationfor impressing a single phase of the said supply upon each device of the series thereat, respectively, for conditioning the said devices thereat sequentially and independently with respect to each other, means included at each station for controlling the conductivity of the devices of the series periodically and cyclically so that each device can be rendered conductive only at exclusive and predetermined intervals and rendered non-conductive at all other times, means at one of the stations for rendering a predetermined number of the conditioned devices conductive aperiodically at the said intervals for initiating control signals, means at a second one of said stations for renderin the conditioned devices thereat conductive for segregating the said control signals for control purposes, means at the first mentioned station for rendering at least one of the said remaining devicesconductive for initiating continuously a series of synchronizing signals at those intervals when the last mentioned device is conditioned so that it can be rendered conductive, and means responsive to said synchroniizng signals at the second mentioned station including means for controlling the generation of the multi-phase power supply thereat.

I CLYDE J. FITCH. 

